Appliqués are of considerable interest today for commercial and military application. Flight tests have been conducted on paintless aircraft technologies that use an outer surface of a material such as appliqué. These appliqués save production costs, support requirements, and aircraft weight while providing significant environmental advantages. Some of these appliqués are described in greater detail in U.S. Pat. No. 6,177,189, assigned to the assignee of the present invention, which is incorporated by reference. Further, some commercial airlines, including Western Pacific, use appliqués to convert their transports into flying billboards.
An appliqué provides an advantage of covering a surface with a hydrophobic or superhydrophobic material that may also provide rain erosion resistance. This material is easily applied and removed. This results in a reduction in aircraft maintenance and improves service life.
In addition to the above advantages, appliqués may also provide protection against lightning strikes. Lightning strikes may potentially cause damage to aircraft, especially composite aircraft. To reduce this damage, appliqués may incorporate a layer of a conductive metal foil to reduce damage from these lightning strikes by spreading out the charge of the lightning strike over a large surface area and by directing the charge away from more critical aircraft components. The metal foil may be solid, patterned or a combination of solid and patterned in the appliqué so as to reduce and divert the discharge of the lightning strike. A description of an appliqué providing such protection against lightning strikes is described in U.S. Pat. Pub. No. 2006/0051592, filed Sep. 19, 2005, U.S. Pat. Pub. No. 2005/0181203, filed Sep. 15, 2004 and U.S. Pat. No. 4,352,142, filed Apr. 15, 1981, assigned to the assignee of the present invention, and incorporated herein by reference.
Up to this time, however, appliqués have been limited in the functions and advantages that they provide, such as lightning strike protection, and an opportunity exists to increase the number of functions that may be provided by appliqués.
Currently, electrical devices are placed on, inside or within the aircraft surface. Electrical connections to these electrical devices have been by hard wiring provided by narrow wires or bundles of wires carried internal or external to the aircraft skin. If the wires are placed on the interior of the aircraft, it is necessary to drill holes through the aircraft skin to connect the wires to external electrical devices and may necessitate a re-certification of the aircraft. In most cases, hard wires cannot be placed external to the aircraft skin because of aerodynamic and safety considerations.
Narrow, thin connections such as those provided by standard flexible thin circuitry may provide a solution to problems associated with hard wiring by placing the connections on the exterior of the aircraft skin in such a manner that the connections are both aerodynamic and safe. Additionally, such circuitry connections must be made resistant to impact, aircraft fluids, water, a wide range of temperature fluctuations, abrasion and UV exposure. Thin circuitry may be applied by printing with conductive inks or etching from sputtered metal films. However, circuitry external to the aircraft skin is readily damaged by physical contact and distortion and elongation of the film, and is prone to electrical overheating.
A solution to these problems may be realized by using appliqués containing sections of foil that provide a large area circuit. The foil sections of these appliqués may provide a robust electrical connection to devices including deicing resistors, aircraft monitoring equipment, solar cells and other power sources, sensors, and lights, some of which may be directly embedded within the appliqué while limiting intrusion into the structure of the aircraft in addition to providing lightning strike protection.
By making an electrical connection through large area sections of the foil that are part of an appliqué, a more robust system may be obtained, since a part of the foil providing electrical connectivity may be damaged and still allow the foil to provide electrical connectivity to a device. Additionally, large area sectioned circuitry foils may allow for elongation of the films containing the circuitry without breaking the electrical paths within the circuitry and help the circuitry foil to conform to a complex 3-dimensional surface such as an aircraft skin.
Most importantly, the appliqué containing the sectioned foil, in addition to providing a large area circuit, may also provide additional functions including, but not limited to, protection against lightning strikes, deicing, and equipment monitoring.
Therefore, a need exists to provide an appliqué that can perform a wide range of functions including, but not limited to, electrical circuitry, lightning strike protection, deicing, and equipment monitoring.
Other features and advantages of the present invention will be apparent from the following more detailed description, taken in conjunction with the accompanying drawing which illustrates, by way of example, the principles of the invention.